Media-tight control device for a motor vehicle and method for producing the control device

ABSTRACT

The disclosure relates to a control device in a motor vehicle. The control device includes a housing cover with a peripheral edge region, and a planar, electrical connecting apparatus with integrated conductor tracks. The housing cover, in the edge region, is cohesively connected at least to the connecting apparatus and forms a cavity with the connecting apparatus. The control device also includes at least one electronic component within the cavity. The connecting apparatus electrically connects the at least one electronic component to electronic components outside the cavity. The housing cover is encapsulated by injection molding in a media-tight manner by a polymer beyond the peripheral edge region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PCT ApplicationPCT/EP2016/069397, filed Aug. 16, 2016, which claims priority to GermanApplication DE 10 2015 217 576.6, filed Sep. 15, 2015. The disclosuresof the above applications are incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to a control device for a motor vehicle and to amethod for producing said control device.

BACKGROUND

In motor vehicle technology, components such as transmission systems,engine systems or brake systems are increasingly being primarilycontrolled electronically. This involves a development toward integratedmechatronic control systems, that is to say for integrated controlelectronics and the associated electronic components such as sensors orvalves into the transmission, the engine or the brake system. Therefore,control devices generally have a large number of electronic componentswhich are connected to other components outside the control device. Inthe case of “on-site electronics systems” of this kind, these controlsystems are no longer accommodated in a separate protected electronicscompartment and therefore have to withstand corresponding environmentalinfluences and mechanical, thermal and chemical loads. For this purpose,they are normally inserted into special housings.

An electronic connection from the inside of the housing to the outsideof the housing is needed in order to allow a reliable connection tocomponents which are positioned outside the housing.

The circuit carriers for control systems of this kind are generallyconstructed, introduced into a housing and this housing is then closed.An example of this is described in DE 10 2007 038 331 A1. However, thishousing structure does not guarantee absolute leak-tightness againstdiffusion and/or permeation. Over the course of time, harmful gases canreach the circuit carrier and lead to corrosion of metal.

In an alternative design, the entire circuit structure for protectingthe circuit carrier is completely encapsulated with a moldingcomposition. An example of this is described in DE 10 2011 082 537 A1.The process management of the molding process has to be preciselycomplied with in this case. Otherwise, if unhoused electroniccomponents, so-called bare dies, which are electrically connected to thecircuit carrier by gold wire connections are used, so-called bondingwire drifting phenomena may occur. Furthermore, the coefficient ofthermal expansion of the molding material has to be precisely matched tothe entire structure comprising carrier substrate, components etc.Otherwise gaps may form between the molding composition and thestructure under temperature loads.

A further possible way of sealing off the circuit chamber is welding thehousing to a stainless steel cover. This method is comparatively costlyand the electrical connections have to be routed from the circuitcarrier, through the stainless steel housing, to the outside, inparticular via glass bushings. Faults in the process can easily occur inthis case. Furthermore, gases which are produced in the interior of thehousing by the welding process can be discharged again only withdifficulty.

SUMMARY

The disclosure provides a control device for a motor vehicle. Thecontrol device offers complete protection of the circuit and the circuitcarrier against harmful gases and against aggressive media such astransmission oil, and at the same time leads to a reduction inproduction costs in comparison to previously known control devices.

The control device includes a housing cover with a peripheral planaredge region and a planar, electrical connecting apparatus withintegrated conductor tracks. The housing cover, in the edge region, iscohesively connected at least in sections to the connecting apparatus soas to form a connecting seam and forms a cavity with the connectingapparatus. The cohesive connection between the housing cover and theconnecting apparatus is established, for example, by adhesive bonding,lamination, or soldering.

On the connecting apparatus, at least one electronic component isarranged within the cavity, and the connecting apparatus electricallyconnects this electronic component to electronic components outside thecavity. In this case, the housing cover is encapsulated by injectionmolding in a media-tight manner with a polymer over its entire surfaceand beyond the peripheral edge region, wherein the housing cover ispreferably composed of plastic or of metal, and the polymer is designedpredominantly as molding material, as adhesive or resin.

The electronic components include, for example, capacitors, coils or amicroprocessor. The electronic components are generally electricallyconnected to one another by conductor tracks of the connecting apparatusand/or by bonded gold wires.

The housing cover protects the electronic components in the interior ofthe control device housing against oils, such as aggressive oils, andalso harmful gases and chemicals. Furthermore, the electronic componentsare protected against salts or processing residues. The oils, gases,salts and/or residues are present, for example, in a transmission onwhich or within which the control device is arranged. The correspondingconductor tracks are also protected by the housing cover. To this end,the cover, as already mentioned, is connected in a cohesive manner tothe connecting apparatus in the edge region such that, together with theconnecting apparatus, a closed-off cavity is formed around theelectronic components. In addition, the housing cover is, for example,completely encapsulated by injection molding in a media-tight mannerwith a polymer beyond the peripheral edge region in this case. As aresult, a housing cover which is not composed of media-tight material,and is therefore generally also more cost-effective, can also be used.Therefore, the control device structure is hermetically sealed off fromthe surrounding area.

In contrast to covers which are connected in an interlocking manner, nofluids and/or gases can enter the cavity, for example, in the region ofthe connecting seam. Therefore, the electronic components are sealed andsealed off from the environment. In addition, rubber-like seals whichare used, for example, in covers which are attached in an interlockingmanner can be dispensed with. These seals would not guarantee completegas-tightness since the gases can diffuse through seals of this kind toa considerable extent over the course of time.

For example, the chemicals or gases include sulfur compounds, as aresult of which sulfides can be produced. Sulfides are at leastpartially electrically conductive and would form deposits on unprotectedelectronic components, the conductor tracks of the connecting operatorsand/or the gold wires. This may result in chemical reactions with thesulfides. For example, the conductor tracks of the connecting apparatus,such as silver conductor tracks, oxidize with the sulfur compounds. Inthis case, line resistances and/or functions of the electroniccomponents can change and negatively influence, for example, theshifting behavior of a transmission. Furthermore, gases of this kind cancause changes in signal, so that, for example, the control deviceapparatus makes incorrect evaluations.

Therefore, overall, the service life and the accuracy of the controldevice are improved by the described structure. Furthermore, thedescribed control device can be implemented as a prefabricated modulefor an on-site application, such as in the transmission or as an add-oncontrol device for example.

In some implementations, the connecting apparatus is designed as aprinted circuit board with at least one layer. The printed circuit boardis, for example, a fiber-reinforced plastic printed circuit board or aceramic printed circuit board. However, an HDI (High DensityInterconnect) printed circuit board which is of very compactconfiguration could also be used. Here, the continuous printed circuitboard projects beyond the entire peripheral edge region of the housingcover and at the same time forms the base of the housing. This results,for example, in a planar structure of the control device.

In order to additionally reinforce this structure or to compensate for acurvature of the structure in the region of the printed circuit board,which curvature occurs under certain circumstances, polymer can beadditionally sprayed onto that side of the printed circuit board whichis facing away from the housing cover in the region which corresponds tothe connecting seam.

In order to reduce or to equalize the difference in level between theedge region of the cover and the printed circuit board in the region ofthe injection-molded encapsulation, the peripheral edge region of thehousing cover runs in a corresponding peripheral groove in the printedcircuit board. As a result, the risk of a gap forming in theinjection-molded encapsulation in the region of the connecting point isreduced.

In some implementations, the connecting apparatus is arranged in part asa separate circuit carrier in the interior of the cavity, where the atleast one electronic component, such as capacitor, coil ormicroprocessor, is arranged on the separate circuit carrier. Theelectronic components are electrically connected to one another, forexample, by conductor tracks of the circuit carrier and/or by bondedgold wires. The separate circuit carrier is, for example, afiber-reinforced plastic printed circuit board or a ceramic printedcircuit board with one or more layers in each case. However, as analternative, an HDI (High Density Interconnect) printed circuit boardwhich is of very compact configuration for construction-related reasonscould also be used.

The at least one electronic component on the separate circuit carriermay be electrically connected to electronic components outside thecavity by a separate printed circuit board. The separate printed circuitboard used is, for example, a flexible printed circuit board which isformed over the entire surface area, with a cutout for receiving theseparate circuit carrier, or is of strip-like design. In this example,the separate circuit carrier and the separate printed circuit board arearranged on a common carrier plate which projects beyond the entireperipheral edge region of the housing cover. Here, the cavity in thecontrol device is substantially surrounded by the housing cover and thecarrier plate. In general, the carrier plate is manufactured from ametal, such as aluminum, because of its stiffness and heat dissipationcapability. If the separate printed circuit board used is a flexiblefilm or foil, it may be laminated onto the carrier plate. If theflexible printed circuit board is formed over the entire surface areawith a cutout for receiving the circuit carrier, the flexible printedcircuit board is substantially overlapped over the entire periphery bythe edge region of the housing cover. If the flexible printed circuitboard is of strip-like design, the flexible printed circuit board isonly partially covered by the peripheral edge region of the housingcover generally transversely to the conductor tracks.

In some implementations, the peripheral edge region of the housing coverruns in a corresponding peripheral groove in the carrier plate. As aresult, the difference in level between the edge region of the cover andthe carrier plate in the region of the injection-molded encapsulation isreduced or even equalized, and therefore the risk of a gap forming inthe polymer in the region of the connecting seam is reduced.

In some implementations, an opening is arranged in the housing cover,making it possible for a protective gel to be introduced into the cavitythrough the opening before the injection-molded encapsulation. Theprotective gel covering at least the electronic components on theconnecting apparatus. In some examples, the entire cavity is cast withthe protective gel. After the protective gel is introduced, the openingin the housing cover is closed in a leak-tight manner by an adhesive, aspherical closure apparatus, or a polymer material. The protective gelprovides additional protection of the electronics in the control device.

The disclosure also provides a method for producing the control device.The method includes providing the connecting apparatus on which theelectronic components are arranged, and providing the housing cover. Themethod also includes cohesively connecting the housing cover to theconnecting apparatus in such a way that the housing cover forms, withthe connecting apparatus, a closed-off cavity in which the electroniccomponents are located. The method also includes encapsulating thehousing cover by injection molding with a polymer in such a way that thepolymer which provides encapsulation by injection molding extends beyondthe peripheral edge region of the housing cover.

In some implementations, a protective gel, which covers at least theelectronic components on the connecting apparatus, is introduced intothe cavity through an opening in the housing cover before the housingcover is encapsulated by injection molding with a polymer. In someexample, the entire cavity is cast with the protective gel. After theprotective gel is introduced, the opening in the housing cover is closedin a leak-tight manner by an adhesive, a spherical closure apparatus, ora polymer material.

The details of one or more implementations of the disclosure are setforth in the accompanying drawings and the description below. Otheraspects, features, and advantages will be apparent from the descriptionand drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a section through a control device having a continuousprinted circuit board as the connecting apparatus.

FIG. 2 shows a control device as in FIG. 1, with polymer applied to bothsides.

FIG. 3 shows a section through a control device having a separatecircuit carrier and a separate printed circuit board.

FIG. 4 shows a control device as in FIG. 3, but with a groove in thecarrier plate.

FIG. 5 shows a control device as in FIG. 3, but with protective gel inthe cavity.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIGS. 1 and 2 and, respectively, 3 to 5 show schematic side views of acontrol device according to two different design principles, where FIG.1 and FIG. 2 show the first design principle and FIGS. 3 and 5 show thesecond design principle. First of all, the common features of the twodesign principles will be described, before the differences arediscussed.

In some implementations, a control device of an automatic transmissionof a motor vehicle evaluates measurement values from sensors, such asHall sensors, and controls shifting of the automatic transmission basedon the measurement values. As an alternative, the control device mayalso be used for other purposes, such as in an engine of a motor vehiclefor example.

Each control device has a connecting apparatus 2, 3. A plurality ofelectronic components 7 are arranged on the connecting apparatus 2, 3.In some examples, the electronic components include capacitors, coils,at least one microprocessor and/or other components. The electroniccomponents 7 are electrically connected to one another, for example, bybonded gold wires and/or conductor tracks of the connecting apparatus 2,3.

In order to protect the electronic components 7 and the correspondingconductor tracks, a housing cover 4, in its peripheral edge region 8, isconnected in a cohesive manner to the connecting apparatus 2, 3 so as toform a peripheral connecting seam 6. The cohesive connection between thehousing cover 4 and the connecting apparatus 2, 3 is established byadhesive bonding. However, this connection can also be realized bylamination or soldering for example. The housing cover 4 is selectivelymanufactured from metal or plastic.

The housing cover 4 and the connecting apparatus 2, 3 enclose aclosed-off cavity 9. Therefore, the cohesive connecting seam 6 is formedaround the electronic components 7 in a coherent manner between thehousing cover 4 and the connecting apparatus 2, 3.

The connecting apparatus 2, 3 electrically connects the electroniccomponents 7 in the interior of the control device to electroniccomponents, not shown

here, outside the cavity 9 or control device. The housing cover 4 isencapsulated by injection molding in a media-tight manner by a polymer 5completely and beyond its peripheral edge region 8. As a result, ahousing cover 4 which is not composed of media-tight material, and istherefore generally also more cost-effective, can also be used.

In this case, the peripheral edge region 8 of the housing cover 4 isencapsulated by injection molding with a polymer 5 at least in theregion of the connecting seam 6 between the housing cover 4 and theconnecting apparatus 2, 3, for example, in such a way that the polymer 5extends, beyond the edge region 8 in the direction facing away from thehousing cover 4, extending over the connecting apparatus 2, 3, forexample, at least over the width of the edge region 8. The width of theinjection-molded encapsulation depends, amongst other things, on thetype of polymer 5 used and on the surface condition of the areas whichare encapsulated by injection molding. For example, the edge region 8and the connecting apparatus 2, 3 can each be of planar design. As analternative, the edge region 8 and the connecting apparatus 2, 3 caneach have a corresponding structure which, in the assembled state, canlead to improved strength and leak-tightness of the connection,primarily over the service life. This ensures that the region of theconnecting seam 6 between the housing cover 4 and the connectingapparatus 2, 3 is sufficiently covered with the polymer material 5, andtherefore the control device structure is hermetically sealed off forexample, in this region, from the surrounding area, for example oils,such as aggressive oils, and also harmful gases and chemicals. Thepolymer 5 is designed as a molding material, or alternatively thereto asan adhesive or as a resin.

The differences between the two design principles according to FIGS. 1to 5 will be explained in the text which follows.

In the example shown in FIG. 1, the connecting apparatus is designed asa printed circuit board 2 with at least one layer. The printed circuitboard 2 is, for example, a fiber-reinforced plastic printed circuitboard, a ceramic printed circuit board or an HDI printed circuit board.Here, the continuous printed circuit board 2 projects beyond the entireperipheral edge region 8 of the housing cover 4 and at the same timeforms the base of the control device housing. This results, for example,in a planar structure of the control device.

In order to additionally reinforce the control device structure or tocompensate for a curvature of the structure in the region of the printedcircuit board 2, which curvature occurs under certain circumstances,polymer 5 may be additionally sprayed onto that side of the printedcircuit board 2 which is facing away from the housing cover 4 in theregion 10 which corresponds to the connecting seam 6, as shown in FIG.2.

In the example shown in FIG. 3, the connecting apparatus 2, 3 includes aseparate circuit carrier 2, on which all of the electronic components 7are arranged, and a separate printed circuit board 3 by means of whichthe electronic components 7 in the interior of the control device areelectrically connected to electronic components, not shown, outside thecontrol device. The separate circuit carrier 2 and the separate printedcircuit board 3 are connected by bonding wires here. The separatecircuit carrier 2 and the separate printed circuit board 3 are arrangedon a common carrier plate 1 which projects beyond the entire peripheraledge region 8 of the housing cover 4. Here, the cavity 9 issubstantially surrounded by the housing cover 4 and the carrier plate 1.

In some examples, the separate circuit carrier 2 is designed as afiber-reinforced plastic printed circuit board or, alternatively, as aceramic printed circuit board or HDI printed circuit board with one ormore layers in each case. However, other examples of a circuit carriercan also be used. The electronic components 7 are electrically connectedto one another, for example, by bonded gold wires and/or conductortracks of the separate circuit carrier 2.

The separate printed circuit board 3 used, may be a flexible printedcircuit board which is composed of polyimide. This flexible printedcircuit board 3 is designed either as a closed area, with a cutout forreceiving the circuit carrier 2, or is of strip-like design.

In some examples, the carrier plate is manufactured from a metal, suchas aluminum, because of its rigidity and heat dissipation requirements.The separate circuit carrier 2 and the separate printed circuit board 3are usually adhesively bonded or laminated onto the carrier plate 1. Ifthe flexible printed circuit board 3 is formed over the entire surfacearea, the flexible printed circuit board is substantially overlappedover the entire periphery by the edge region 8 of the housing cover 4.

If the flexible printed circuit board 3 is of strip-like design, theflexible printed circuit board is overlapped only in sections, generallytransversely to the conductor tracks of the printed circuit board 3, bythe peripheral edge region 8 of the housing cover 4 as a result of itsdesign. The connecting seam 6 therefore extends over the peripheral edgeregion 8 on one side and over the strips of the printed circuit board 3or over the carrier plate 1 on the other side.

FIG. 5 shows a control device as in FIG. 3, but the peripheral edgeregion 8 of the housing cover 4 runs in a corresponding peripheralgroove 11 in the carrier plate 1. As a result, the difference in levelbetween the edge region 8 and the carrier plate 1 in the region of theinjection-molded encapsulation (i.e., polymer 5) is reduced orequalized, and therefore the risk of a gap forming in the polymer 5 inthe region of the connecting seam 6 is reduced.

A groove of this kind would accordingly be feasible in the printedcircuit board 2 in the first design principle according to FIGS. 1 and 2too.

FIG. 5 shows a control device as in FIG. 3, but an opening 12 isarranged in the housing cover 4, a protective gel 13 having beenintroduced into the cavity 9 through the opening, the protective gelgenerally covering at least the electronic components 7 on theconnecting apparatus 2, before the encapsulation by injection moldingwith polymer 5. Here, the entire cavity 9 is cast with the protectivegel 13. After the protective gel 13 is introduced, the opening 12 in thehousing cover 4 has been closed in a leak-tight manner by an adhesive, aspherical closure apparatus or a polymer material. The protective gel 13provides additional protection of the electronics in the control device.

Introduction of a protective gel 13 in this way would also be feasiblein the first design principle according to FIGS. 1 and 2.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims.

What is claimed is:
 1. A control device in a motor vehicle, comprising:a housing cover including a peripheral edge region; a planar, electricalconnecting apparatus with integrated conductor tracks; a connecting seamformed by cohesively connecting the edge region of the housing cover tothe connecting apparatus so as to form a connecting seam, the housingcover forms a cavity with the connecting apparatus; at least oneelectronic component within the cavity, wherein the at least oneelectronic component is electrically connected to electronic componentsoutside the cavity by way of the connecting apparatus; and wherein thehousing cover is encapsulated by injection molding in a media-tightmanner by a polymer beyond the peripheral edge region.
 2. The controldevice of claim 1, wherein the connecting apparatus is designed as aprinted circuit board with at least one layer, the printed circuit boardprojects beyond the peripheral edge region of the housing cover.
 3. Thecontrol device of claim 2, wherein polymer is additionally sprayed ontothat side of the printed circuit board which is facing away from thehousing cover in the region which corresponds to the connecting seam. 4.The control device of claim 2, wherein the peripheral edge region of thehousing cover runs in a peripheral groove in the printed circuit board.5. The control device of claim 1, wherein the connecting apparatus isdesigned as a separate circuit carrier in an interior of the cavity,wherein the at least one electronic component which is electricallyconnected to electronic components outside the cavity by a separateprinted circuit board is arranged on the separate circuit carrier, andwherein the separate circuit carrier and the separate printed circuitboard are arranged on a common carrier plate which projects beyond theperipheral edge region of the housing cover.
 6. The control device ofclaim 5, wherein the separate printed circuit board is designed as aflexible printed circuit board.
 7. The control device of claim 5,wherein the separate printed circuit board is overlapped at least insections by the peripheral edge region.
 8. The control device of claim5, wherein the carrier plate is composed of metal.
 9. The control deviceof claim 5, wherein the peripheral edge region of the housing cover runsin a peripheral groove in the carrier plate.
 10. The control device ofclaim 1, wherein the polymer is designed as molding material, asadhesive or resin.
 11. The control device of claim 1, wherein thehousing cover is composed of plastic or of metal.
 12. The control deviceof claim 1, wherein the cohesive connection between the housing coverand the connecting apparatus is established by adhesive bonding,lamination or soldering.
 13. The control device of claim 1, furthercomprising: an opening arranged in the housing cover; and a protectivegel being introduced into the cavity through the opening, the protectivegel at least covering the electronic components on the connectingapparatus.
 14. The control device of claim 13, wherein the opening isclosed by an adhesive, a spherical closure apparatus, or polymermaterial.
 15. A method for producing a control device apparatus, themethod comprising: providing a connecting apparatus on which electroniccomponents are arranged; providing a housing cover, cohesivelyconnecting the housing cover to the connecting apparatus in such a waythat the housing cover and the connecting apparatus form a closed-offcavity in which the electronic components are located; and encapsulatingthe housing cover by injection molding with a polymer in such a way thatthe polymer which provides encapsulation by injection molding extendsbeyond the peripheral edge region of the housing cover.
 16. The methodof claim 15, further comprising: introducing a protective gel coveringat least the electronic components on the connecting apparatus into thecavity through an opening in the housing cover before the housing coveris encapsulated by injection molding, and sealing the opening in aleak-tight manner.